henderson



Jan. 24, 1956 J. E. HENDERSON 2,732,514

ELECTRON TUBE Filed Dec. 50, 1944 k S i w INVENTOR JOSEPH E. HENDERSON ATTORNEY ted Stat s Pae O ELECTRON TUBE Joseph E. Henderson, Seattle, Wash.

Application December 30, 1944, Serial No. 570,690

' 7 Claims. (Cl. 313-246) This invention relates in general to electronic tubes and particularly to a photoelectric electronic relay.

.An object is to provide animproved relay tube having a photosensitive cathode and one or more control grids.

Another object is to provide a relay tube of simple, easily manufactured construction which is of such ruggedness as to be capable of withstanding relatively. heavy mechanical stresses and violent shock loads without inter: v

fering with its operation.

A further object is toprovide a combined photoelectric tube and relay tube, gaseous or otherwise, which maybe used in various circuits ordinarily requiring two or more tubes. My improved tube therefore is of value in photoelectrically controlled devices of a wide variety, since it makes possible a reduction of size as well as cheaper con:

on the lines 2-2 and 4-4, respectively, of Figure l, and.

looking in the direction of the arrows.

Figure 3 is a plan view of the.cathode.

Figure 5 is a longitudinal sectionalview corresponding to Figure 1 but showing a somewhat modified construction. Y t

Figure 6 is a cross-sectional view taken substantially on the line 6-6 of Figure 5 and looking in the direction of the arrows.

Figure 7 is a longitudinal sectional viewcorresponding to Figures 1 and 5 but showing another somewhat modified construction. Q 4

In the construction shown inFigure l, envelope 1 may be of glass or other suitable material and'is of substantially cylindrical and symmetrical form. A disc-like cathode 2 is supported by lead-in metal rod 3 at one end of the envelope, a press 4 being formed around rod 3 to make a strong and leak-proof fit. Rod 3 may be of Dumet or similar material having a coefiicient of expansion approximately equal to that of-the glass. 'Grid 5 is supported by Dumet or other lead-in element 6, and press 7 is formed around element 6 to produce a rigid, leak-proof fit. Anode 8, preferably also in the shape of a disc, is supported at the other end of the envelope on lead-in rod 9, which is sealed in position by press 10. The anode and cathode, and their supporting lead-in rods, are coaxially disposed within and with respect to the envelope. The grid is also symmetrically mounted with respect to the axis of the assembly, and the mass of the grid is so slight that it can develop relatively very little inertia, even if the tube is rapidly accelerated or decelerated.

The surface of cathode 2, facing grid 5, is made photosensitive by depositing thereon a thin layer of antimony and then a covering layer of caesium which may be released by heat from caesium capsule 11 attached to anode 2,732,514 Patented Jan. 24, 1956 2 8. The metal of the base of cathode 2 may be of nickel or any suitable material, and anode 8 may be of the same metal.

After evacuating tube 1, as through a tubulation, not shown, a certain amount of gas such as mercury vapor, krypton, argon, or the like, is introduced to produce a suitable pressure which is' determined from the kind of gas and spacings of the parts used. The tubulation is then sealed off. It is understood, of course, that the usual degasifying treatment is to beused.

If this tube is then used in a circuit as a relay, it will conduct virtually no current as long as grid 5 is maintained at a potential below a certain critical value, depending upon the characteristics of the tube. If, however, cathode 2 is illuminated and the potential ofgrid 5 with respect to the cathode rises above the critical value, then the contained gas will suddenly become ionized due to bombardment by electrons emitted by cathode 2 as a result of photoemissive action. When this happens, the tube will conduct relatively large currents if anode 8 is maintained at a positive potential with respect to cathode 2. The grid does' not control the conductivity of the tube once it has started. Control can be regained by re-' ducing the anode voltage to zeroor to some critical value.

This relay has outstanding advantages over other types employing heated filaments since no A battery is required, and therefore there is no energy drain until the device operates. It'will accordingly be useful under ordinarily deleterious temperature conditions such as thoseexisting in the tropics, and the shelf life'of the A battery does not have to be considered.

In many applications it may also be of advantage that the tube is operative only when there is light on the cathode.

Gas pressures and spacings, cathode to grid, and grid to anode, are adjusted for operation in the desired voltage region. By utilization of this control, preferably with an num or the equivalent, is attached to cathode 2 so thatelectron emission will be greatly increased from oxide or other spots" on element 12. The emission starts with cathode 2 and :then largely switches over to spotting electrode 12.

Another marked advantage of. my novel tube is that it may be used in. many circuits in which a photoelectric T tube is employed. The functions-of a relay and a phototube canbe combined in the onetube, thereby saving cost ,andxreducing space required, if'this is desirable. As an illustration, the grid 5 can be used as an anode in a photoelectric tube circuit in which cathode 2 is also included.

In addition,.a relay or other circuit can include cathode 2 and anode 8.

In the modification shown in Figs. 5 and 6, the envelope is formed of two sections of glass tubing, 1a and 1b,

arranged end to end to form a continuous enclosure. such enclosure being closed at its ends by metallic end caps, 20 and 8a. The caps also constitute cathode and anode elements, respectively. An annular grid supporting element 6a is supported by and arranged between the tubing sections la-lb, and projects into the space within the envelope assembly where it is provided with cylindrical portions, 6b6c, adapted to telescope into and locate the abutting ends of the tubing sections. Element 6a also carries an inwardly projecting flange, 6d, upon which the grid element, 5a, rests. The functions thus obtained stem from the fact that the parts 6a and 6b, 6c in Fig. 5 consist of two flat rings, one bisecting the other, so that 6b, 6c is perpendicular to 6a. The rim of the latter provides an exposed place for access to a wire connection. The

grid element includes a resilient wire annulus, biased to bear outwardly against the flange, 6c, and so retain itself in position. This engagement also provides electrical connection between the grid and the portion, 6a, of the grid-supporting ring assembly, which last-mentioned portion is accessible from outside the envelope, the grid connection being made to it. v

The end caps 2a, 8a, which, as previously stated, also serve as cathode and anode elements, respectively, are peripherally flanged to overlie the ends of the glass tubing sections, and the tubing sections are sealed to the cod cap and to the grid supporting ring by cement or other suitable means. A wedge-shaped spotting electrode portion, 12a, is attached to the cathode cap, 2a, and functions similarly to the portion, 12, of the embodiment first described. The cathode cap is also perforated, as indicated at 15, to permit evacuation of the envelope through the tubulation attached to the outside of the cap.

The use of metallic end caps with straight cylindrical glass sections makes fora very rigid construction, and the glass. sections may be of heavy gauge, since they do not have to be blown. The method of supportingv the grid is also such as to provide the utmost rigidity. The assembly is therefore highly resistant to physical abuse and stress.

In the further modification shown in Fig. 7, the enclosure constituting the envelope is formed of a single length of cylindrical glass tubing, 1g, closed at its ends by caps 2g, 8g, so shaped that they may be conveniently formed of simple sheet metal stampings. In this embodiment the cap 2g does not in itself act as the cathode, but serves as a support for the cathode element, 2h, formed as a plate of nickel or other suitable material. welded or otherwise attached to the cap and carrying the pointed spotting electrode, 12g. The grid, 5g. is supported in the envelope by means of a rod, 6g, extending through a press, 7g, in the side wall. The caps are cemented or otherwise sealed to the glass tubing section and a tubulation, 16g, overlies opening g in the cap, 2g, to permit evacuation.

A continuation opening 1511 is also formed in the cathode plate 211.

I claim:

1. In an electron tube construction, an envelope fabricated into a continuous enclosure, and a control element located crosswise of the envelope, said control element having a self-embodied portion biased to bear outwardly against the envelope thereby to retain said element in position.

2. In an electron tube construction, an envelope fabricated into a continuous enclosure, a grid-locating element sealed in said envelope, said element including an annular retaining section carried by said locating element and lying within the envelope, and a control element formed of resilient material therefor inherently biased to bear sealed in said envelope said element including an annular retaining section carried by said locating element and 1ying within the envelope, and a control element consisting of a grid spanning the space across the grid-locating element, said control element including a resilient annulus to which the components of the grid are connected, the resilience of the annulus putting pressure against the annular retaining section thereby to retain the control element in position.

4. In an electron tube construction, a tubular envelope, capped at its ends and having cathode and anode elements emplaced on the respective end caps inside of the envelope, a control element also inside of the envelope, situated medially of the ends and consisting of grid components spanning the diameter of the envelope, said control element including a split, resilient annulus to which the ends of the components are connected and which tends to spring outwardly, and a grid-locating element having a supporting element incorporated in the tubular envelope structure and including an inwardly projecting flange on which the control element is rested, and having a cylindrical portion against which the annulus presses.

5. In an electron tube construction having an annular grid-locating element consisting of a fiat-ring, remotely capped tubular sections between the near ends of which the flat ring is sealed leaving the rim of the ring externally exposed to form a rest and an abutment; in combination, a control element set upon the rest, said element being bounded by a split annulus exerting a retaining pressure on the abutment.

6. In an electron tube construction, an envelope fabricated into a continuous enclosure, and a control element located crosswise of the envelope, said control element consisting of a grid element and a resilient wire annulus for said element, being split to form contiguous ends rcsponding to the resilience of the annulus with an outward bias against the envelope to retain said grid element in position.

7. In an electron tube construction, an envelope fabricated into a continuous enclosure, and a control element located crosswise of the envelope, said control element consisting of a grid element having a plurality of grid components all being spaced substantially parallel to each other, and an encompassing resilient ring to which the ends of the components are joined to complete the grid, said ring being split in line with one of the spaces between components thereby allowing the ring unrestricted ontward flexure into gripping engagement with the envelope.

References Cited in the file of this patent UNITED STATES PATENTS 1,980,198 Gray Nov. 13, l934 2,104,825 Shrader Jan. 11, 1938 2,116,224 Sternberg May 3, 1938 2,151,781 Lindenblad Mar. 28, 1939 2,178,837 Krahl Nov. 7, 1939 2,251,653 Berg, Jr. Aug. 5, l94l 2,353,743 McArthur July 18, 194-4 2,431,402 lanes Nov. 25, 1947 2,438,587 Taylor Mar. 30, 1948 FOREIGN PATENTS 304,325 Germany Oct. 2, 1919 

